Large-effective-mode-area low-loss optical fiber with optimized cladding components

Abstract

The present invention provides a large-effective-mode-area low-loss optical fiber with optimized cladding components, which comprises a core layer and a cladding comprising, from the inside to the outside, a first sinking layer, a second sinking layer, an optional third sinking layer, and an outer cladding. In the present invention, phosphorus and aluminum are co-doped in the optical fiber cladding, to form a tetrahedron [AlPO4] in glass, thus optimizing the viscosity of the cladding while effectively reducing the refractive index of the cladding, without causing increased hydrogen loss. The process is simple, and highly repeatable.

What is claimed is: 
     
       1. A large-effective-mode-area low-loss optical fiber with optimized cladding components, comprising a core layer and a cladding comprising, from inside to outside, a first sinking layer, a second sinking layer and an outer cladding, wherein
 the second sinking layer is a multi-doped quartz inner cladding, and dopants comprise fluorine, aluminum and phosphorus, wherein aluminum and phosphorus are doped in an amount of 0-10 mol %, and have a continuous distribution, the molar ratio of aluminum and phosphorus is 0.7-1.3:1, aluminum and phosphorus are co-doped in glass to form a [AlPO 4 ] tetrahedron, the contribution of the [AlPO 4 ] tetrahedron to the refractive index of the second sinking layer is −0.8%-0, the contribution of fluorine to the refractive index of the second sinking layer is −0.05%-0, the relative difference Δn2 in refractive index of the second sinking layer is −0.85%-0, and the radius R2 of the second sinking layer is 8-35 μm. 
 
     
     
       2. The optical fiber according to  claim 1 , wherein the first sinking layer is a pure quartz layer or a multi-doped quartz inner cladding, and when the first sinking layer is a multi-doped quartz inner cladding, dopants comprise fluorine, aluminum and phosphorus, wherein aluminum and phosphorus are doped in an amount of 0-10 mol %, and have a continuous distribution, the molar ratio of aluminum and phosphorus is 0.8-1.2:1, aluminum and phosphorus are co-doped in glass to form a [AlPO 4 ]] tetrahedron, the contribution of the [AlPO 4 ] tetrahedron to the refractive index of the first sinking layer is −0.8%-0, the contribution of fluorine to the refractive index of the first sinking layer is −0.05%-0, the relative difference Δn1 in refractive index of the first sinking layer is −0.85%-0, and the radius R1 of the first sinking layer is 6-20 μm. 
     
     
       3. The optical fiber according to  claim 1 , wherein the outer cladding is a pure quartz cladding or a multi-doped quartz cladding, and when the outer cladding is a multi-doped quartz cladding, dopants comprise fluorine, aluminum and phosphorus, wherein aluminum and phosphorus are doped in an amount of 0-5 mol %, and have a continuous distribution, the molar ratio of aluminum and phosphorus is 0.9-1.1:1, the contribution of fluorine to the refractive index of the outer cladding is −0.02%-0, the contribution of the [AlPO 4 ] tetrahedron to the refractive index of the outer cladding is −0.4%-0, the relative difference Δn4 in refractive index of the outer cladding is −0.42%-0, and the radius R4 of the outer cladding is 62.5 μm. 
     
     
       4. The optical fiber according to  claim 1 , wherein the core layer is a multi-doped silica core layer, and dopants comprise germanium and fluorine, wherein the contribution of germanium to the refractive index of the core layer is 0-0.3%, the contribution of fluorine to the refractive index of the core layer is −0.05%-0, and the dopants have a continuous distribution in the core layer, the relative difference Δn0 in refractive index of the core layer is 0-0.25%, and the radius R0 of the core layer is 5-8 μm. 
     
     
       5. The optical fiber according to  claim 1 , wherein fluorine is introduced through freon or silicon tetrafluoride, the phosphorus is phosphorus pentoxide and introduced through the raw material phosphorus trichloride, aluminum is alumina and introduced through the raw material aluminum chloride. 
     
     
       6. The optical fiber according to  claim 1 , wherein the cladding further comprises a third sinking layer, located between the second sinking layer and the outer cladding. 
     
     
       7. The optical fiber according to  claim 6 , wherein the third sinking layer is a multi-doped quartz inner cladding, and dopants comprise fluorine, aluminum and phosphorus, wherein aluminum and phosphorus are doped in an amount of 0-5 mol %, and have a continuous distribution, the molar ratio of aluminum and phosphorus is 0.7-1.3:1, the contribution of fluorine to the refractive index of the third sinking layer is −0.05%-0, the contribution of the [AlPO 4 ] tetrahedron to the refractive index of the third sinking layer is −0.4%-0, the relative difference Δn3 in refractive index of the third sinking layer is −0.45%-0, and the radius R3 of the third sinking layer is 8-62.5 μm. 
     
     
       8. The optical fiber according to  claim 1 , wherein the attenuation of the optical fiber at a wavelength of 1550 nm is less than or equal to 0.18 dB/km. 
     
     
       9. The optical fiber according to  claim 1 , wherein the attenuation of the optical fiber at a wavelength of 1550 nm is less than or equal to 0.16 dB/km. 
     
     
       10. The optical fiber according to  claim 1 , wherein after the optical fiber is reacted for at least 16 h in 0.01 vol % H 2  at 70° C., the change in attenuation of the optical fiber at a wavelength of 1550 nm is less than or equal to 0.01 dB/km.